Insecticidal N-(substituted phenyl)-N&#39;-benzoyl ureas

ABSTRACT

N-(Substituted phenyl)-N&#39;-benzoyl ureas of the formula ##STR1## in which R is chlorine or fluorine, 
     R&#39; is chlorine, fluorine or hydrogen, and 
     R&#34; is fluorine, chlorine or bromine. 
     Which possess insecticidal properties.

The present invention relates to and has for its objects the provision of particular new N-(substituted phenyl)-N'-benzoyl ureas which possess insecticidal properties, active compositions in the form of mixtures of such compounds with solid and liquid dispersible carrier vehicles, and methods for producing such compounds and for using such compounds in a new way expecially for combating pests, e.g. insects, with other and further objects becoming apparent from a study of the within specification and accompanying examples.

It is already known from German Published Specification DOS No. 2,123,236 that certain benzoylureas, such as, for example, N-(2,6-dichlorobenzoyl)-N'-(4-chlorophenyl)-(Compound A) and -3,4-dichlorophenyl)-urea (Compound B), possess insecticidal properties.

The present invention provides, as new compounds, the N-phenyl-N'-benzoyl-ureas of the general formula ##STR2## in which R is chlorine or fluorine,

R' is chlorine, fluorine or hydrogen, and

R" is fluorine, chlorine or bromine.

The compounds of the formula (I) have been found to possess powerful insecticidal properties.

Surprisingly, the new N-phenyl-N'-benzoyl-ureas according to the invention have a substantially better insecticidal action than the nearest compounds of analogous structure and of the same type of action previously known from the state of the art. This is the more surprising since, according to the state of the art, a 4-trifluoromethyl-substitution results in the best insecticidal action in active compounds containing phenyl and the introduction of a further substituent only results in a diminution of the action [see J. Agr. Food Chem., Vol. 21, No. 3 (1973) page 351, Examples 37, 38 and 39 and page 354, Example 8]. The compounds according to the invention thus represent a genuine enrichment of the art.

The present invention also provides a process for the preparation of an N-phenyl-N'-benzoyl-urea of the formula

I, in which

A. A 3-TRIFLUOROMETHYL-4-HALOGENO-ANILINE OF THE GENERAL FORMULA ##STR3## is reacted with a benzoylisocyanate of the general formula ##STR4##

in which formulae

R, R' and R" have the above-mentioned meanings, if appropriate in the presence of a solvent, or

b. a 3-trifluoromethyl-4-halogeno-phenylisocyanate of the general formula ##STR5## is reacted with a benzamide of the general formula ##STR6##

in which formulae

R, R' and R" have the above-mentioned meanings, if appropriate in the presence of a solvent.

If, following process variant (a), 4-chloro-3-trifluoromethylaniline and 2-chlorobenzoylisocyanate are used as starting materials, and following process variant (b), 4-chloro-3-trifluoromethyl-phenylisocyanate and 2,6-difluorobenzamide are used as starting materials, the courses of the reactions can be represented by the following formula schemes: ##STR7##

The 2-chlorobenzoylisocyanate to be used as a starting material is known from the literature and can, like the other benzoylisocyanates (III), be prepared in accordance with generally customary processes [see A. J. Speziale et al., J. Org. Chem. 30 (12), pages 4306-4307 (1965)].

2,6-Difluorobenzamide and the other benzamides (V) are known and can be prepared in accordance with generally customary processes (see Beilstein's Handbook of Organic Chemistry, Volume 9, page 336). The 4-halogeno-3-trifluoromethylanilines (II) can be prepared in accordance with generally customary process. Thus, for example, 4-bromo-3-trifluoromethylaniline can be prepared in accordance with P. Tarrant and M. R. Lilyquist, Am. Soc. 75, page 3034 (1953). The amino group can be converted to the isocyanate group in accordance with generally customary processes, for example by reaction with phosgene, whereby the isocyanates of the general formula (IV) are obtained.

The following may be mentioned as examples of the benzoylisocyanates (III) and benzamides (V) to be reacted in accordance with the process: 2-chloro-, 2-fluoro-, 2,6-dichloro- and 2,6-difluoro-benzoylisocyanate and also 2-chloro-, 2-fluoro-, 2,6-dichloro- and 2,6-difluoro-benzamide.

The process variants for the preparation of the compounds according to the invention are preferably carried out in the presence of suitable solvents and diluents. Practically all inert organic solvents can be used for this purpose, especially aliphatic and aromatic, optionally chlorinated, hydrocarbons, such as benzene, toluene, xylene, benzine, methylene chloride, chloroform, carbon tetrachloride and chlorobenzene; ethers, for example diethyl ether, dibutyl ether and dioxan; ketones, for example acetone, methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone; and nitriles, such as acetonitrile and benzonitrile.

The reaction temperature can be varied within a fairly wide range. In general the reaction is carried out at between 0° and 120° C and preferably at from 40° to 85° C.

In general, the reaction is allowed to take place under normal pressure.

To carry out the process, the reactants are preferably employed in equimolar amounts. An excess of one or other reactant produces no significant advantages.

The 4-halogeno-3-trifluoromethylisocyanates (IV) to be employed in process variant (b) can be used as such or without intermediate isolation, in the form of their reaction mixture which is obtained from the reaction of amine with phosgene. To this reaction mixture, in one of the above-mentioned solvents, is added the benzamide, for example 2,6-difluorobenzamide. The reaction is carried out under the desired conditions and the product which separates out is isolated in the usual manner by filtration, washing and, if appropriate, recrystallization.

The compounds are obtained in a crystalline form having a sharp melting point.

As already mentioned, the N-phenyl-N'-benzoyl-ureas according to the invention are distinguished by an excellent insecticidal activity, while having a favorable level of toxicity to warm-blooded animals and being well tolerated by plants. They are active against plant pests and, in the veterinary medicine field, against ectoparasites.

For this reason, the compounds according to the invention can be employed successfully as pesticides in plant protection and in the veterinary medicine field.

To the sucking insects there belong, in the main, aphids (Aphididae) such as the green peach aphid (Myzus persicae), the bean aphid (Doralis fabae), the bird cherry aphid (Rhopalosiphum padi), the pea aphid (Macrosiphum pisi) and the potato aphid (Macrosiphum solanifolii), the currant gall aphid (Cryptomyzus korschelti), the rosy apple aphid (Sappaphis mali), the mealy plum aphid (Hyalopterus arundinis) and the cherry black-fly (Myzus cerasi); in addition, scales and mealybugs (Coccina), for example the oleander scale (Aspidiotus hederae) and the soft scale (Lecanium hesperidum) as well as the grape mealybug (Pseudococcus maritimus); thrips (Thysanoptera), such as Hercinothrips femoralis, and bugs, for example the beet bug (Piesma quadrata), the red cotton bug (Dysdercus intermedius), the bed bug (Cimex lectularius), the assassin bug (Rhodnius prolixus) and Chagas' bug (Triatoma infestans) and, further, cicadas, such as Euscelis bilobatus and Nephotettix bipunctatus.

In the case of the biting insects, above all there should be mentioned butterfly and moth caterpillars (Lepidoptera) such as the diamond-back moth (Plutella maculipennis), the gypsy moth (Lymantria dispar), the browntail moth (Euproctis chrysorrhoea) and tent caterpillar (Malacosoma neustria); further, the cabbage moth (Mamestra brassicae) and the cutworm (Agrotis segetum), the large white butterfly (Pieris brassicae), the small winter moth (Cheimatobia brumata), the green oak tortrix moth (Tortrix viridana), the fall armyworm (Laphygma frugiperda) and cotton worm (Prodenia litura), the ermine moth (Hyponomeuta padella), the Mediterranean flour moth (Ephestia kuehniella) and greater wax moth (Galleria mellonella).

Also to be classed with the biting insects are beetles (Coleoptera), for example the granary weevil (Sitophilus granarius = Calandra granaria), the Colorado beetle (Leptinotarsa decemlineata), the dock beetle (Gastrophysa viridula), the mustard beetle (Phaedon cochleariae), the blossom beetle (Meligethes aeneus), the raspberry beetle (Byturus tomentosus), the bean weevil (Bruchidius = Acanthoscelides obtectus), the leather beetle (Dermestes frischi), the khapra beetle (Trogoderma granarium), the flour beetle (Tribolium castaneum), the northern corn billbug (Calandra or Sitophilus zeamais), the drugstore beetle (Stegobium paniceum), the yellow mealworm (Tenebrio molitor) and the saw-toothed grain beetle (Oryzaephilus surinamensis), and also species living in the soil, for example wireworms (Agriotes spec.) and larvae of the cockchafer (Melolontha melolontha); cockroaches, such as the German cockroach (Blattella germanica), American cockroach (Periplaneta americana), Madeira cockroach (Leucophaea or Rhyparobia maderae), oriental cockroach (Blatta orientalis), the giant cockroach (Blaberus giganteus) and the black giant cockroach (Blaberus fuscus) as well as Henschoutedenia flexivitta; further, Orthoptera, for example the house cricket (Gryllus domesticus); termites such as the eastern subterranean termite (Reticulitermes flavipes) and Hymenoptera such as ants, for example the garden ant (Lasius niger).

The Diptera comprise essentially the flies, such as the vinegar fly (Drosophila melanogaster), the Mediterranean fruit fly (Ceratitis capitata), the house fly (Musca domestica), the little house fly (Fannia canicularis), the black blow fly (Phormia regina) and bluebottle fly (Calliphora erythrocephala) as well as the stable fly (Stomoxys calcitrans); further, gnats, for example mosquitoes such as the yellow fever mosquito (Aedes aegypti), the northern house mosquito (Culex pipiens) and the malaria mosquito (Anopheles stephensi).

The active compounds according to the instant invention can be utilized, if desired, in the form of the usual formulations or compositions with conventional inert (i.e. plant compatible or herbicidally inert) pesticide diluents or extruders, i.e. diluents, carriers or extenders of the type usable in conventional pesticide formulations or compositions, e.g. conventional pesticide dispersible carrier vehicles such as gases, solutions, emulsions, suspensions, emulsifiable concentrates, spray powders, pastes, soluble powders, dusting agents, granules, etc. These are prepared in known manner, for instance by extending the active compounds with conventional pesticide dispersible liquid diluent carriers and/or dispersible solid carriers optionally with the use of carrier vehicle assistants, e.g. conventional pesticide surface-active agents, including emulsifying agents and/or dispersing agents, whereby, for example, in the case where water is used as diluent, organic solvents may be added as auxiliary solvents. The following may be chiefly considered for use as conventional carrier vehicles for this purpose: aerosol propellants which are gaseous at normal temperatures and pressures, such as Freon; inert dispersible liquid diluent carriers, including inert organic solvents, such as aromatic hydrocarbons (e.g. benzene, toluene, xylene, alkyl naphthalenes, etc.), halogenated, especially chlorinated, aromatic hydrocarbons (e.g. chlorobenzenes, etc.), cycloalkanes, (e.g. cyclohexane, etc.), paraffins (e.g. petroleum or mineral oil fractions), chlorinated aliphatic hydrocarbons (e.g. methylene chloride, chloroethylenes, etc.), alcohols (e.g. methanol, ethanol, propanol, butanol, glycol, etc.) as well as ethers and esters thereof (e.g. glycol monomethyl ether, etc.), amines (e.g. ethanolamine, etc.), amides (e.g. dimethyl formamide, etc.), sulfoxides (e.g. dimethyl sulfoxide, etc.), acetonitrile, ketones (e.g. acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), and/or water; as well as inert dispersible finely divided solid carriers, such as ground natural minerals (e.g. kaolins, clays, alumina, silica, chalk, i.e. calcium carbonate, talc, attapulgite, montmorillonite, kieselguhr, etc.) and ground synthetic minerals (e.g. highly dispersed silicic acid, silicates, e.g. alkali silicates, etc.); whereas the following may be chiefly considered for use as conventional carrier vehicle assistants, e.g. surface-active agents, for this purpose: emulsifying agents, such as non-ionic and/or anionic emulsifying agents (e.g. polyethylene oxide esters of fatty acids, polyethylene oxide ethers of fatty alcohols, alkyl sulfates, alkyl sulfonates, aryl sulfonates, albumin hydrolyzates, etc., and especially alkyl arylpolyglycol ethers, magnesium stearate, sodium oleate, etc.); and/or dispersing agents, such as lignin, sulfite waste liquors, methyl cellulose, etc.

Such active compounds may be employed alone or in the form of mixtures with one another and/or with such solid and/or liquid dispersible carrier vehicles and/or with other known compatible active agents, especially plant protection agents, such as other insecticides, or nematocides, acaricides, fungicides, bactericides, rodenticides, herbicides, fertilizers, growth-regulating agents, etc., if desired, or in the form of particular dosage preparations for specific application made therefrom, such as solutions, emulsions, suspensions, powders, pastes, and granules which are thus ready for use.

As concerns commercially marketed preparations, these generally contemplate carrier composition mixtures in which the active compound is present in an amount substantially between about 0.1-95% by weight, and preferably 0.5-90% by weight, of the mixture, whereas carrier composition mixtures suitable for direct application or field application generally contemplate those in which the active compound is present in an amount substantially between about 0.0001-10%, preferably 0.01-1%, by weight of the mixture. Thus, the present invention contemplates overall compositions which comprise mixtures of a conventional dispersible carrier vehicle such as (1) a dispersible inert finely divided carrier solid, and/or (2) a dispersible carrier liquid such as an inert organic solvent and/or water, preferably including a surface-active effective amount of a carrier vehicle assistant, e.g. a surface-active agent, such as an emulsifying agent and/or a dispersing agent, and an amount of the active compound which is effective for the purpose in question and which is generally between about 0.0001-95%, and preferably 0.01-95%, by weight of the mixture.

The active compounds can also be used in accordance with the well known ultra-low-volume process with good success, i.e. by applying such compound if normally a liquid, or by applying a liquid composition containing the same, via very effective atomizing equipment, in finely divided form, e.g. average particle diameter of from 50-100 microns, or even less, i.e. mist form, for example by airplane crop spraying techniques. Only up to at most about a few liters/hectare are needed, and often amounts only up to about 15 to 1000 g/hectare, preferably 40 to 600 g/hectare, are sufficient. In this process it is possible to use highly concentrated liquid compositions with said liquid carrier vehicles containing from about 20 to about 95% by weight of the active compound or even the 100% active substance alone, e.g. about 20-100% by weight of the active compound.

Furthermore, the present invention contemplates methods of selectively killing, combating or controlling pests, e.g. insects, which comprises applying to at least one of correspondingly (a) such insects, and (b) the corresponding habitat thereof, i.e. the locus to be protected, e.g. to a growing crop, to an area where a crop is to be grown or to a domestic animal, a correspondingly combative or toxic amount, i.e. insecticidally effective amount, of the particular active compound of the invention alone or together with a carrier vehicle as noted above. The instant formulations or compositions are applied in the usual manner, for instance by spraying, atomizing, vaporizing, scattering, dusting, watering, squirting, sprinkling, pouring, fumigating, dusting, encrusting, and the like.

It will be realized, of course, that the concentration of the particular active compound utilized in admixture with the carrier vehicle will depend upon the intended application. Therefore, in special cases it is possible to go above or below the aforementioned concentration ranges.

The unexpected superiority and outstanding activity of the particular new compounds of the present invention are illustrated, without limitation, by the following examples:

EXAMPLE 1

Phaedon larvae test

Solvent: 3 parts by weight of dimethylformamide

Emulsifier: 1 part by weight of alkylaryl polyglycol ether

To produce a suitable preparation of active compound, 1 part by weight of the active compound was mixed with the stated amount of solvent containing the stated amount of emulsifier and the concentrate was diluted with water to the desired concentration.

Cabbage leaves (Brassica oleracea) were sprayed with the preparation of the active compound until dripping wet and were then infested with mustard beetle larvae (Phaedon cochleariae).

After the specified periods of time, the degree of destruction was determined in %: 100% means that all of the beetle larvae had been killed whereas 0% means that none of the beetle larvae had been killed.

The active compounds, the concentrations of the active compound, the evaluation times and the results can be seen from the following Table 1:

                  TABLE 1                                                          ______________________________________                                         (Phaedon larvae test)                                                                                          Degree                                                                Active   of des-                                                               compound truction                                                              concen-  in %                                                                  tration  after 3                                        Active compound        in %     days                                           ______________________________________                                          ##STR8##              0.1 0.01 100  15                                        (known)                                                                         ##STR9##              0.1 0.01 100 100                                         ##STR10##             0.1 0.01 100 100                                         ##STR11##             0.1 0.01 100 100                                         ##STR12##             0.1 0.01 100 100                                        ______________________________________                                    

EXAMPLE 2

Plutella test

Solvent: 3 parts by weight of dimethylformamide

Emulsifier: 1 part by weight of alkylaryl polyglycol ether

To produce a suitable preparation of active compound, 1 part by weight of the active compound was mixed with the stated amount of solvent containing the stated amount of emulsifier and the concentrate was diluted with water to the desired concentration.

Cabbage leaves (Brassica oleracea) were sprayed with the preparation of the active compound until dew moist and were then infested with caterpillars of the diamond-back moth (Plutella maculipennis).

After the specified periods of time, the degree of destruction was determined as a percentage: 100% means that all of the caterpillars were killed whereas 0% means that none of the caterpillars were killed.

The active compounds, the concentrations of the active compound, the evaluation times and the results can be seen from the following Table 2:

                  TABLE 2                                                          ______________________________________                                         (Plutella test)                                                                                                Degree                                                                Active   of des-                                                               compound truction                                                              concen-  in %                                                                  tration  after 8                                        Active compound        in %     days                                           ______________________________________                                          ##STR13##             0.1 0.01  65  0                                         (known)                                                                         ##STR14##             0.1 0.01 0.001                                                                          100 100  15                                    (known)                                                                         ##STR15##             0.1 0.01 0.001                                                                          100 100 100                                     ##STR16##             0.1 0.01 0.001                                                                          100 100 100                                     ##STR17##             0.1 0.01 0.001                                                                          100 100 100                                     ##STR18##             0.1 0.01 0.001                                                                          100 100 100                                     ##STR19##             0.1 0.01 0.001                                                                          100 100 100                                     ##STR20##             0.1 0.01 0.001                                                                          100  100 100                                    ##STR21##             0.1 0.01 0.001                                                                          100 100 100                                    ______________________________________                                    

EXAMPLE 3

Laphygma test

Solvent: 3 parts by weight of dimethylformamide

Emulsifier: 1 part by weight of alkylaryl polyglycol ether

To produce a suitable preparation of active compound, 1 part by weight of the active compound was mixed with the stated amount of solvent and the stated amount of emulsifier and the concentrate was diluted with water to the desired concentration.

Cotton leaves (Gossypium hirsutum) were sprayed with the preparation of the active compound until dew-moist and were then infested with caterpillars of the owlet moth (Laphygma exigua).

After the specified periods of time, the destruction in % was determined. 100% means that all of the caterpillars had been killed while 0% indicates that no caterpillars had been killed.

The active compounds, the concentrations of the active compound, the evaluation times and the results can be seen from the following Table 3:

                  TABLE 3                                                          ______________________________________                                         (Laphygma test)                                                                                                Degree                                                                Active   of des-                                                               compound truction                                                              concen-  in %                                                                  tration  after 8                                        Active compound        in %     days                                           ______________________________________                                          ##STR22##             0.001 0.0001 0.00001                                                                    100  50  0                                     (known)                                                                         ##STR23##             0.001 0.0001 0.00001                                                                    100 100 100                                     ##STR24##             0.001 0.0001 0.00001                                                                    100 100 100                                    ______________________________________                                    

EXAMPLE 4

Test with parasitic fly larvae

Solvent: 35 parts by weight of ethylene polyglycol monomethyl ether; 35 parts by weight of nonylphenol polyglycol ether

To produce a suitable preparation of active compound, 30 parts by weight of the active substance in question were mixed with the stated amount of solvent which contained the above-mentioned proportion of emulsifier and the concentrate thus obtained was diluted with water to the desired concentration.

About 20 fly larvae (Lucilia cuprina) were introduced into a test tube which contained approx. 2 cm³ of horse muscle. 0.5 ml of the preparation of active compound was applied to this horse meat. After 24 hours, the degree of destruction in % was determined. 100% means that all of the larvae had been killed and 0% means that no larvae had been killed.

The active compounds investigated, the concentrations of the active compound used and the results obtained can be seen from Table 4 which follows:

                  TABLE 4                                                          ______________________________________                                         Test on Lucilia cuprina, resistant                                                                    Active                                                                         compound                                                                       concen-                                                                        tration  Action                                         Active compound        in ppm   in %                                           ______________________________________                                          ##STR25##             1000      0                                             (known)                                                                         ##STR26##             100  30  10                                                                             100 100  0                                     ______________________________________                                    

The process of the present invention is illustrated by the following preparative Examples.

EXAMPLE 5 ##STR27##

A solution of 18.2 g (0.1 mole) of 2-chlorobenzoylisocyanate in 50 ml of toluene was added dropwise at 40° C to 19.5 g (0.1 mole) of 4-chloro-3-trifluoromethylaniline in 200 ml of toluene. The batch was stirred for 1 hour at 40° C. After cooling, the product which had precipitated was filtered off and washed first with toluene and then with petroleum ether. After drying, 21.0 g (55% of theory) of analytically pure N-(4-chloro-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea of melting point 164° C were obtained.

EXAMPLE 6 ##STR28##

A solution of 9.2 g (0.05 mole) of 2,6-difluorobenzoylisocyanate in 50 ml of toluene was added dropwise at 40° C to a solution of 9.8 g (0.05 mole) of 4-chloro-3-trifluoromethylaniline in 100 ml of toluene. The batch was stirred for 1 hour at 40° C. The substance which separated out was filtered off after cooling the reaction mixture to 20° C, and washed with toluene and petroleum ether. After drying, 18.0 g (95% of theory) of N-(4-chloro-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea of melting point 220° C were obtained.

The following compounds were obtained by procedures analogous to those described in Examples 5 and 6.

                                      TABLE 5                                      __________________________________________________________________________                                     Physical                                                                       data    Yield                                  Compound                        (Melting                                                                               (% of                                  No.   Formula                   point, ° C)                                                                     theory)                                __________________________________________________________________________            ##STR29##                154     55                                     4                                                                                     ##STR30##                182     47                                     5                                                                                     ##STR31##                216     76                                     6                                                                                     ##STR32##                222     78                                     7                                                                                     ##STR33##                213     82                                     __________________________________________________________________________

It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention. 

What is claimed is:
 1. An N-phenyl-N'-benzoyl-urea of the formula ##STR34## in which R is chlorine or fluorine,R' is chlorine, fluorine or hydrogen, and R" is fluorine, chlorine and bromine.
 2. The compound according to claim 1, wherein such compound is N-(4-chloro-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea of the formula ##STR35##
 3. The compound according to claim 1, wherein such compound is N-(4-chloro-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea of the formula ##STR36##
 4. The compound according to claim 1, wherein such compound is N-(4-fluoro-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea of the formula ##STR37##
 5. The compound according to claim 1, wherein such compound is N-(4-bromo-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea of the formula ##STR38##
 6. The compound according to claim 1, wherein such compound is N-(4-fluoro-3-trifluoromethylphenyl)-N'-(2,6-dichlorobenzoyl)-urea of the formula ##STR39##
 7. The compound according to claim 1, wherein such compound is N-(4-bromo-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea of the formula ##STR40##
 8. The compound according to claim 1, wherein such compound is N-(4-fluoro-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea of the formula ##STR41##
 9. A composition containing an amount of the compound of claim 1 effective to kill Plutella Maculipennis in admixture with a diluent.
 10. A method of combating the insect Plutella Maculipennis which comprises applying to said insect or its habitat an insecticidally effective amount of a compound according to claim
 1. 11. A method according to claim 10, in which said compound isN-(4-chloro-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea, N-(4-chloro-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea, N-(4-fluoro-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea, N-(4-bromo-3-trifluoromethylphenyl)-N'-(2-chlorobenzoyl)-urea, N-(4-fluoro-3-trifluoromethylphenyl)-N'-(2,6-dichlorobenzoyl)-urea, N-(4-bromo-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea, or N-(4-fluoro-3-trifluoromethylphenyl)-N'-(2,6-difluorobenzoyl)-urea. 